脊髓背角 HCN4 - KCC2 在糖尿病性神经痛中作用的研究

HCN通道功能失调与糖尿病周围神经病变密切相关。HCN4通道特异性表达于脊髓背角抑制性神经元，我们预实验观察到，鞘内给予HCN通道拮抗剂降低糖尿病神经痛大鼠脊髓HCN4表达的同时增加KCC2表达，并缓解疼痛。近年研究表明，脊髓背角KCC2（胞内高钾驱动的K+-Cl-外向共转运体）表达降低所致的“GABA向兴奋性转化”促进了疼痛的发生。由此，我们推测：糖尿病时HCN4通道激活诱发的K+外流可抑制KCC2功能，导致脊髓背角GABAA受体功能向兴奋性转化，促进糖尿病神经痛的发生与维持。本项目拟敲减脊髓HCN4基因，观察其对糖尿病大鼠痛阈值、背角KCC2和GABAA受体表达、GABA释放的影响；离体实验观察HCN4是否通过KCC2途径调节背角神经元GABAA受体激活电流及兴奋性，并分析其信号机制。该研究将会为人们理解疼痛提供一个新的模式系统，为开发以HCN4通道为靶点的新型镇痛药提供理论依据。

It is considered that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels dysfunction promotes the generation of diabetic peripheral neuropathy. HCN4 channels are expressed in neurons within the superficial spinal dorsal horn. In our earlier experiments, we found that intrathecal administration of HCN channels antagonist markedly suppressed the expression of HCN4 channels, raised KCC2 expression, and relieved diabetic neuropathic pain. Recent research shows that impaired GABAA receptor-mediated inhibition caused by decreased expression of KCC2 in the spinal cord promoted the generation of neuropathic pain. For this reason, we speculate that K+ outflow induced by activation of HCN4 channel suppress the function of KCC2, which consequently impair GABAA receptor-mediated inhibition and promote the development and maintenance of diabetic neuropathic pain. In this proposal, we want to explore the effect of HCN4 channels on pain threshold, KCC2 and GABAA receptors expression, and GABA release in dorsal horn of streptozotocin-induced diabetic rats. Furthermore, we will explore the role of HCN4 channels in regulating the action of GABAA receptors in dorsal horn neurons by adjusting KCC2 function. The research will clarity the role of HCN4 channels in diabetic neuropathic pain, and provide some evidence for developing effective analgesics based on HCN4 channels as new therapeutic targets.